Liquid fuel pumps



Oct. 30, 1962 R. H. BELL 3,060,859

LIQUID FUEL PUMPS Filed March 7. 1960 7W s B 18 a a E 1 I I Q i I 8 *I' 5 11 if V H? a 3,060,859 LIQUID FUEL PUMPS Robert Henry Jail, Kings Heath, Birmingham, England,

assignor to Joseph Lucas (industries) Limited, Birmingharn, England Filed Mar. 7, 1966, Ser. No. 13,044 Claims priority, application Great Britain Mar. 13, 1959 1 Claim. (Cl. 163-457) This invention relates to liquid fuel pumps of the kind commonly termed boost pumps and comprising a casing having an inlet and an outlet and adapted to be mounted in a normally submerged position within a fuel tank, an electric motor within the casing, said motor having a rotor which is rotatable about a normally vertical axis and which is open to fuel within the casing, and a rotary impeller connected to the lower end of the rotor for induciug a fiow of fuel from the inlet to the outlet.

In such a pump the presence of fuel within the gap between the rotor and stator of the motor imposes an undesirable drag upon the rotor, and the object of the present invention is to provide means for minimizing this drag.

According to the invention in a fuel pump of the kind specified the inlet to the casing is in communication with an inlet chamber below the impeller, and in the shaft of the latter is formed an axially extending bore which at its upper end is in communication with passages opening into the gap between the rotor and stator, the arrangement being such that in operation air or vapour from a fuel vortex formed beneath the impeller can escape upwardly through the passages, and then upwardly through said gap to a vent at the upper end of the casing.

An example of the invention is illustrated in sectional side elevation in the accompanying drawing.

Referring to the drawing, there is provided a multipart casing 1 which is adapted to be secured within the bottom of a fuel tank 2 in the wing of an aircraft. Near the lower end of the casing is an inlet 3 through which fuel can flow from the tank to an inlet chamber 4 in the lower end of the casing, whilst at a position near the upper end of the chamber 4 is a tangentially directed outlet 5 adapted for connection to a fuel supply pipe of the aircraft. Moreover, slidably surrounding the lower part of the casing is an annular valve member 6 which is movable by angularly spaced screws 7 operable from the exterior of the tank to a position to close the inlet 3.

The lower part of the casing is adapted to be secured to the marginal edge of the tank 2 surrounding a hole in the bottom of the latter, and the lower end of the casing is closed by a detachable cover forming a part of a multi-part body 8 extending upwardly into the casing. Within an annular recess in the upper part of the body 8 are mounted the stator windings 9 of a three-phase electric motor, these windings being sealed from the fuel by a thin stainless steel tube 10 of cylindrical form covering the inner side of the recess. Within the tube 10, and spaced by a small gap therefrom, is a rotor 11 which is rotatable about a normally vertical axis. The rotor shaft 12 extends downwardly into the upper part of the chamber 4, which is of scroll-like cross-section, and secured to the lower end of the shaft 12 is a rotary impeller 13 which is adapted in operation to induce a flow of fuel from the chamber 4 to the outlet 5. In the lower end of the shaft 12 is formed an axially extending passage 14 which at its upper end communicates with a plurality of radially 3,%,859 Patented Oct. 30, 1962 extending passages 15 opening into the lower end of the annular gap between the rotor 11 and the tube 12.

In operation air or vapour in the fuel vortex formed in the chamber 4 below the impeller 13 can escape upwardly through the passages 14, 15 into the gap, and thence upwardly to a vent 16 at the top of the casing, thereby minimising the drag of fuel on the rotor which is normally submerged within and open to the fuel within the casing.

Associated with the vent 16 is a spring-loaded valve member 17 which is held from its seating by a rod 18 which co-operates with a screw-threaded drain plug 19 engaging the cover at the lower end of the body.

If it is required to remove the motor for maintenance or replacement the screws 7 are first actuated to close the inlet 3 to the casing. The drain plug 19 is then removed to empty the casing and at the same time effect closing of the vent 16. Thereafter by releasing a plurality of screws holding the cover in position the complete body together with the motor and impeller can be withdrawn without emptying the fuel from the tank.

Having thus described my invention what I claim as new and desire to secure by Letters Patent is:

For use in a fuel tank, a liquid fuel boost pump comprising in combination a casing which is adapted to be mounted in a normally submerged vertical position within the fuel tank, and which is provided at its upper end with a vent opening, at its lower end with a fuel inlet chamber, and at a position near the upper part of the fuel inlet chamber with a fuel outlet, an electric motor mounted within the casing above the fuel inlet chamber, and having a rotor which is rotatable about a substantially vertical axis, a cylindrical tube which surrounds the rotor and is spaced therefrom by a small annular gap, and a stator which surrounds the tube, and to which the tube is secured so as to seal the adjacent part of the stator from the fuel, a substantially vertical rotary shaft on which the rotor is secured, and which extends from the lower end of the rotor into the upper part of the fuel inlet chamber, and a rotary impeller rigidly united with the lower end of the rotor shaft for inducing fuel flow from the fuel inlet chamber to the outlet, the lower end portion of the rotor shaft being provided with an axial bore which at its lower end is open to the fuel inlet chamber, and with radial passages which at their inner ends communicate with the upper end of the axial bore, and which at their outer ends are open to the annular gap between the rotor and the surrounding tube, so that, when the impeller is driven by the motor, air or vapour from a fuel vortex created beneath the impeller can flow through the axial bore and radial passages in the lower end portion of the rotor shaft to the annular gap between the rotor and the surrounding tube, and then flow upwardly through the said gap to the upper end of the casing from which the air or vapour can escape through the vent opening.

References Cited in the file of this patent UNITED STATES PATENTS 1,143,957 Hansen June 22, 1915 1,897,318 Mcllvaine Feb. 14, 1933 2,370,590 Taylor Feb. 27, 1945 2,575,568 Topanelian Nov. 20, 1951 2,688,946 Jarsaillon Sept. 14, 1954 2,693,148 Doelter Nov. 2, 1954 

